The present invention relates to a shaft apparatus having a shaft, blocks, and a roller bearing.
As a shaft apparatus having a shaft, blocks, and a roller bearing, for example, there is a camshaft apparatus which is rotatably mounted to a cylinder head portion of an internal combustion engine.
When the shaft apparatus is the camshaft apparatus, after a shaft, a predetermined number of cam blocks (corresponding to the blocks), and a roller bearing (for example, a bearing) using a portion of an outer surface of the shaft as an inner ring raceway surface are individually manufactured, the cam blocks and the roller bearing are disposed and fitted to the outer surface of the shaft at predetermined intervals in an axial direction.
In addition, as disclosed in JP2007-192315A and JP2007-187259A, a camshaft apparatus having a structure in which a predetermined number of cam blocks are disposed on an outer surface of a shaft in an axial direction thereof and a roller bearing which is separately provided is mounted on the outer surface of the shaft in a radial direction, is known.
However, at a normal temperature, when the roller bearings using the portion of the outer surface of the shaft as the inner ring raceway surface, and the cam blocks are fitted to the outer surface of the shaft in the axial direction thereof at predetermined intervals, press-fitting marks may be generated by press-fitting the cam blocks to the outer surface of the shaft, and this causes the degradation in performance of the roller bearing. For this reason, the outer surface of the shaft needs to be subjected to a surface treatment such as a heat treatment to obtain a desired hardness, and the roller bearing and the cam blocks are fitted thereto at predetermined intervals by performing a cold fitting. This results in cost increase.
In addition, as disclosed in JP2007-192315A and JP2007-187259A, the roller bearing has to be separately provided to be mounted on the outer surface of the shaft in the radial direction, so that manufacturing and mounting the roller bearings cannot be easily performed.
Further, when the camshaft apparatus in which the cam blocks and the roller bearing are fitted and mounted to the outer surface of the shaft in the axial direction is mounted to the cylinder head portion, in some cases, the roller bearing may unpredictably move in the axial direction of the shaft. In this case, the roller bearing has to be moved and adjusted to a predetermined position in the axial direction of the shaft, and this may cause trouble.
Therefore, a control member which is disposed at a position close to an end portion of an outer ring of the roller bearing to control unpredictable movement of the roller bearing in the axial direction has been proposed.
However, when the control member is disposed at the position close to the end portion of the outer ring of the roller bearing, during the bearing rotation, sliding resistance (friction) between the end portion of the outer ring of the roller bearing and the control member occurs, and this causes degradation in bearing performance.
In general, as a bearing apparatus for a camshaft, for example, as disclosed in JP2007-247875A, there is a bearing apparatus employing a roller bearing instead of a sliding bearing to be disposed between a housing member and a cap member on a camshaft on which a plurality of cam blocks are disposed in an axial direction, in order to reduce torque loss.
In the bearing apparatus, an outer ring of the roller bearing is divided into two portions to be engaged with an arc concave portion of the housing member and an arc concave portion of the cap member, respectively.
In addition, at a cage for refining a number of rollers, a crack is formed in a circumferential direction, so that the cage is mounted along an outer circumference of the camshaft.
In addition, an axially stepped portion for controlling the movement of the roller bearing in the axial direction is provided to the camshaft.
However, in the general bearing apparatus for a camshaft, the axially stepped portion has to be provided to the camshaft by dividing the outer ring of the roller bearing into two portions and forming the crack at the cage in the circumferential direction, so that the structure is complex.